Show simple item record

dc.contributor.authorXu, Y
dc.contributor.authorLebedev, S
dc.contributor.authorMeier, T
dc.date.accessioned2022-05-12T12:00:11Z
dc.date.available2022-05-12T12:00:11Z
dc.date.issued2022
dc.date.submitted2021-11-26
dc.identifier.issn2169-9313
dc.identifier.otherjgrb55632
dc.identifier.other2021jb023701
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/337071
dc.description.abstractAbstract: Surface waves propagating from earthquakes, active sources or within the ambient noise wavefield are widely used to image Earth structure at various scales, from centimeters to hundreds of kilometers. The accuracy of surface‐wave, phase‐velocity measurements is essential for the accuracy of the Earth models they constrain. Here, we identify a finite‐frequency phase shift in the phase travel time that causes systematic errors in time‐domain, phase‐velocity measurements. The phase shift arises from the approximation of monochromatic surface waves with narrow‐band filtered surface waves. We derive an explicit formula of the finite‐frequency phase shift and present a numerical method for its evaluation and for the correction of the measurements. Applications to high‐frequency and long‐period examples show that the phase shift is typically around π/60‐π/16 for the common settings of ambient‐noise imaging studies, which translates to 0.2%–0.8% phase‐velocity measurement errors. The finite‐frequency phase shift depends on the (a) second derivative of the wavenumber with respect to frequency; (b) width of the narrow‐band filter; (c) epicentral or interstation distance; and (d) center frequency of the filter. In conversion to phase velocity, the last two factors cancel out. Frequency‐domain methods for phase‐velocity measurements have the advantage of not producing the finite‐frequency phase shift. Both time‐ and frequency‐domain measurements, however, can be impacted by a break‐down of the far‐field approximation (near‐field phase shift), which our calculations also show. Our method offers an effective means of improving the accuracy of the widely used time‐domain, phase‐velocity measurements via the evaluation of and corrections for the finite‐frequency phase shift.
dc.languageen
dc.publisherAmerican Geophysical Union (AGU)
dc.subjectSeismology
dc.subjectSEISMOLOGY
dc.subjectSurface waves and free oscillations
dc.subjectResearch Article
dc.subjectsurface wave
dc.subjectphase shift
dc.subjectphase velocity measurement
dc.subjectnoise interferometry
dc.titleImaging the Earth Using Time-Domain Surface-Wave Measurements: Evaluation and Correction of the Finite-Frequency Phase Shift
dc.typeArticle
dc.date.updated2022-05-12T12:00:11Z
prism.issueIdentifier5
prism.publicationNameJournal of Geophysical Research: Solid Earth
prism.volume127
dc.identifier.doi10.17863/CAM.84492
dcterms.dateAccepted2022-04-26
rioxxterms.versionofrecord10.1029/2021JB023701
rioxxterms.versionAO
rioxxterms.versionVoR
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/
dc.contributor.orcidXu, Y [0000-0003-0411-6222]
dc.identifier.eissn2169-9356
pubs.funder-project-idEuropean Commission ‐ Horizon2020 (776622)
cam.issuedOnline2022-05-12


Files in this item

Thumbnail
Thumbnail

This item appears in the following Collection(s)

Show simple item record